印度洋、西北太平洋龟螺属和小龟螺属种类的分类及DNA条形码鉴定

近来的研究表明，一些所谓的环球或环极地分布的广布种实际上包含着一些局限性分布的隐存种，物种多样性可能被低估。本文采用形态学和DNA条形码技术相结合的方式，对印度洋和西北太平洋海域的龟螺属(Cavolinia)和小龟螺属(Diacavolinia)的种类进行了分类学研究和物种鉴定。结果表明，线粒体16S rRNA基因数据不支持小龟螺属形态种的划分，分布于西北太平洋的D. grayi、D. vanutrechti、D. pacifica、D. elegans、D. angulosa等多个形态种可能属同一个种，即长吻小龟螺(D. longirostris)。COI基因数据也不支持钩龟螺(C. uncinata)亚种和变形的划分。许多形态特征不能作为种或种下分类单元的区分依据。钩龟螺、球龟螺(C. globulosa)和长吻小龟螺在COI系统树中均形成2个地理支系，其内部可能存在隐存种。西北太平洋海域长吻小龟螺的核基因组中存在线粒体假基因，对DNA条形码分析产生严重干扰。

Taxonomy and DNA barcoding in genera Cavolinia and Diacavolinia from the Indian Ocean and Northwest Pacific Ocean

Some so-called circumglobal and/or circumpolar marine species are proved to be complexes of cryptic species with restricted distributions by molecular analyses. These phenomena imply that marine species diversity has been underestimated. In this study we use shell morphological characteristics together with mitochondrial COI and 16S rRNA gene sequences in order to study the taxonomy and to identify species of genera Cavolinia and Diacavolinia in family Cavoliniidae from the Indian Ocean and Northwest Pacific Ocean. Our results showed that the species delimitation of Diacavolinia is not supported by molecular analyses, those morphospecies (D. grayi, D. vanutrechti, D. pacifica, D. elegans, D. angulosa, etc.) with distinct morphology from northwestern Pacific are a single species, namely D. longirostris. The subdivision of subspecies and/or forms for C. uncinata could not be confirmed by DNA evidence. Phylogenetic analysis of COI revealed two independent geographical lineages for C. uncinata, C. globulosa and D. longirostris respectively, suggesting that these morphspecies may harbour cryptic diversity. Nuclear mitochondrial pseudogene sequences of COI were detected from most individuals of D. longirostris, which can affect the analysis of DNA barcoding.